This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

8148 board base driver testing

Everybody is good:
When I test 8148 bare board code i2c2_io_expander, the code is from 8148 CD, I use CCS for testing.
But print a message is as follows:

  Unable to detect the IO expander on EVM at Slave addr 0x21.
  [CortexA8] Unable to initialize the IO Expander for I2C-2 module on the IO Expander board.
  [CortexA8]      FAIL... error code -1... quitting
I hope to find a better way!!  
 thanks all  .